This invention relates to storage-stable aqueous compositions containing hydrogen cyanamide and propionic acid.
As described in U.S. published patent applications 2007/92581 and 2007/116781 of Rodrigo Rodriguez-Kabana, combinations of hydrogen cyanamide and lower alkanoic acids such as propionic acid provide protection of crops against nematode and insect infections, and weed control, by applying such combinations of ingredients to the soil. That patent application describes tests of combinations of varying amounts of hydrogen cyanamide and propionic acid applied at various application rates.
The working examples in US patent applications 2007/92581 and 2007/116781 were carried out by preparing and relatively quickly applying aqueous solutions containing hydrogen cyanamide and a carboxylic acid (usually propionic acid) to soil. Those patent applications also state that the most economical results will generally be achieved when the hydrogen cyanamide concentration is within the range of from about 0.1% to about 10% by weight, preferably from about 0.3% to about 3% by weight and when the concentration of the monocarboxylic acid is within the range of from about 0.1% to about 20% by weight, and preferably from about 1% to about 10% by weight.
When work was carried out to prepare a formulated product comprising combined solutions of hydrogen cyanamide and propionic acid that would be storage stable for lengthy periods of time, it was found that achieving good storage stability required working outside the above proportions of the two ingredients, as well as maintaining pH within a certain range. Otherwise, adverse effects were found to occur, including production of undesirable impurities and/or precipitation of polymers formed in the decomposition of hydrogen cyanamide through reactions to form dimeric imides or propionates.